"We know of an intelligent species that sent a message. And we know of an intelligent species that received the message. The message could be the Phaistos Disk, or an excerpt of the Voynich Manuscript. Both the sender and the receiver are the same species: humans. Yet, the message is still indecipherable by humans themselves!."

Effective METI strategy requires long-term commitment to transmitting for at least hundreds or thousands of years, depending on the distance to the nearest watchers. Furthermore, individual METI attempts occur at a particular frequency or set of frequencies, which in turn requires that any watcher must be sensitive to that frequency.

We tend to forget that although mathematical discourse is suggested as the message content most likely to be understood because mathematics concepts might be the most universally accessible, the language in which we encode that mathematical content is not at all universal.

Exchanging messages encoding the Fibonacci series with an extraterrestrial astronomer has nothing to do with two planetary civilizations communicating with each other. It has to do with elite members of a given civilization communicating with each other, while the vast majority of the inhabitants of those planets most likely ignore who was Fibonacci. Ethically, it would be more reasonable to send messages to the interstellar medium... only after the entire population of Sol-3 has a knowledge of basic mathematics.

There is no eason for optimism about humans’ ability to understand cosmic cross-cultural communications precisely because our frustrations with Paleolithic art have mostly had to do with the difficulty of understanding the message’s content, that is: our failure in understanding what is being communicated. No one denies that these paintings are the work of human agents, produced through purposeful activity and carrying meaning. But we do not understand the meaning.

While mathematics does not include a grammar as such, surely the concepts and their symbolic representations are systematically related, even if not in the same way as “natural” languages, which means mathematics is as worse as any natural language for interstellar communications within the METI framework.

I am suggesting something more like the following: creating messages such that ETIs could recognize our use of symbols and thus our intelligence, should be possible. Transmission of specifid, objective knowledge through written language is certainly worth trying, but if our experience in deciphering ancient scripts is any indication, it will not be easy for an intelligent being out there to get through the two layers of symbolism to the content of the message. Communicating as the artists (symbolists) of Lascaux did, with but one layer of symbols, won’t get across a concrete, specifid body of data either, but it could convey useful insight about us, perhaps more than a rich, language-based message that can’t be read.

Finney, B. and Bentley, J. A tale of two analogues: learning at a distance from the ancient Greeks and Maya and the problem of deciphering extraterrestrial radio transmissions. Acta Astronautica, 42(10-12), 691-696.